This invention relates to a structure of a lip drive portion of a T-die.
For lamination processes in which a base formed of paper, aluminum foil or plastic is coated with a resin, systems for controlling the coating thickness to improve the quality of worked products as well as to reduce the amount of resin required are in increasing demand. For realization of such systems, development of a T-die in which the rate at which a molten resin flows out can be controlled is an important technical theme.
Conventionally, the rate at which a molten resin flows out of a T-die is adjusted by manually rotating gap adjusting bolts provided in association with the lip portion of the die. Types of drive systems such as a heat bolt system and a servo motor system have been adopted for automatization of this adjustment. The heat bolt system is based on the utilization of thermal expansion of bolts. In this system, however, the time required to perform heating or cooling is long and the responsiveness of the drive system is therefore considerably low. The servo motor system is based on the idea of using a robot system instead of the conventional manual operation. In this system, one or a plurality of motors are used to successively rotate bolts. However, it is not possible to drive all the bolts simultaneously, resulting in an increase in the adjustment time.